Dual-igniter airbag control switch

ABSTRACT

A dual-igniter airbag control switch is provided for a motor vehicle airbag system having a module with a plurality of igniters for causing an airbag to inflate, a diagnostic monitor that determines if a collision is occurring and initiates the igniters, and first and second wires extending between each of the igniters and the monitor for conveying signals between the module and the monitor. The control switch comprises a manually operable switch having portions connected to each of the first wires, for selectively providing continuity in the first wires between the monitor and each of the igniters while in an on position and breaking continuity of the first wires between the monitor and each of the igniters while in an off position. A resistor is connected to each of the second wires and connected to the switch, so that while in the off position, the switch places the resistors in series between the first and second wires and the monitor, each of the resistors having an impedance similar to that of one of the igniters, so as to provide a false indication to the monitor that the continuity exists with the igniters while the switch is in the off position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of pending U.S. patent applicationSer. No. 09/487,532, filed Jan. 19, 2000 entitled “DUAL-IGNITER AIRBAGCONTROL SWITCH,” now U.S. Pat. No. 6,452,436 and is related to, andclaims the benefits of priority from, U.S. Provisional PatentApplication Serial No. 60/116,554, entitled “DUAL-IGNITER AIRBAG CONTROLSWITCH,” filed Jan. 21, 1999.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to electrical control systems and inparticular to devices for controlling automotive supplementary restraintsystems.

BACKGROUND OF THE INVENTION

Since the early 1990's, automobile manufacturers selling cars in theUnited States have been required to equip the cars with supplementaryrestraint systems (airbags). One or more airbags are stored in a forwardposition from the front seated passengers. The vehicle's computer systemmonitors activity to the automobile and initiates necessary deploymentsof the airbag by sending signals through the circuitry to the airbagmodule. By design, the rapid inflation of the airbag protects thepassenger from contact with the vehicle's steering wheel, dashboard,windshield, or other components.

One problem associated with these airbags is the growing safety concernsfor smaller-sized adults, children seated in the front passenger seat ofthe vehicle and children in child safety seats secured in the frontpassenger seat of the vehicle. During the rapid and violent inflation,the airbag has potential to do harm to these particular classes ofpassengers.

Automotive manufacturers have offered switches as an option fordisabling a single airbag having a single igniter. Airbags havingmultiple stage igniters have now been introduced. A multiple stageigniter has two igniters. At a low speed collision, only one of theigniters may ignite to inflate the airbag, while at higher speeds, bothigniters actuate to inflate the bag. The single igniter inflates theairbag with less force than the two combined. To applicant's knowledge,prior to applicant's invention, manufacturers did not offer disablingswitches for dual stage igniters.

SUMMARY OF THE INVENTION

In this invention, a switch allows a request from the vehicle's computersystem to inflate the airbags to be over-ridden and the airbag preventedfrom inflating. Similarly, the switch can be positioned to have thevehicle computer system and airbag modules work without interruption andfunction as normal. In the preferred embodiment, the vehicle's originalcircuit between the computer system and the airbag module is broken. Aswitching device is connected in this created gap, causing the vehicle'scircuit to run through the switching device. The switching device allowsan operator to select whether the computer system's signals will passthrough to the airbag module uninterrupted or be altered. The device maywork as an over-ride of the computer's request by the operator selectedrequest. The switching device works with more than one airbag, and italso is operative with dual stage modules.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front view of one embodiment of a switchconstructed in accordance with the invention.

FIG. 2 is an electrical diagram showing the switch of FIG. 1 connectedto an airbag.

DETAILED DESCRIPTION OF THE INVENTION AND BEST MODE

Referring to FIG. 1, a device 11 for controlling the deployment of anautomotive supplementary restraint system (airbag) is shown. Device 11has a rectangular housing 13 with a two-position (“on” and “off”) keyswitch 15 on a front face. A removable key 17 is provided for actuatingswitch 15. Each position of switch 15 has a light emitting diode (LED)19, 21 for visual confirmation of the position selected. Although switch15 only has two positions in the embodiment shown, it could have otherpositions depending upon the configuration of the airbag system.

Referring now to FIG. 2, an electrical diagram for connecting switch 11to a single airbag module 101 having two igniters 103, 105 is shown.Igniters 103, 105 may be used for various reasons including deploymentof module 101 at different velocities. Typically, a sensor willdetermine the severity of the impact of the vehicle. If the impact isless severe, only one of the igniters 103, 105 ignites to inflate airbag101. If the impact is more severe, both igniters 103, 105 ignite toinflate airbag 101. Each igniter 103, 105 is connected through a pair ofwires 111, 113 and 115, 117, respectively, to a diagnostic monitor orcontroller 119. Monitor 119 is the vehicle's system computer thatmonitors the status of module 101 among other functions. Without device11 (FIG. 1), module 101, igniters 103, 105, and monitor 119 would beconnected directly to one another through wires 111-117. However, withdevice 11, wires 111 and 115 are interrupted at breaks 121, 123,respectively, and connected to device 11.

In the embodiment shown in FIG. 2, switch 15 is a conventionaltriple-pole, double-throw switch. Switch 15 has a first pole 131 withleads or wires 133, 135, 137. Wires 133, 135 are connected to break 121in wire 111, and wire 137 is connected to wire 113. Wire 137 has aresistor 139 that places a load that is the same as the impedance of theairbag module 101 so that the diagnostic monitor 119 does not register afault. Wire 137 also has a fuse 141 in series with resistor 139. Switch15 has a second pole 143 with wires 145, 147, 149. Wires 145, 147 areconnected to break 123 in wire 115, and wire 149 is connected to wire117. Like wire 137, wire 149 has a resistor 151 in series with a fuse153. Switch 15 has a third pole 155 with wires 157, 159, 161. Each wires157, 159 has an LED 19, 21, respectively, which are connected inparallel to a 12-volt DC battery 163. Wire 161 is connected to ground.Preferably, wires 133, 135, 137, 145, 147, 149, 157, 159, 161 exit thehousing 13 through the back face.

In operation, device 11 may be turned off to prevent airbag module 101from deploying in the event of a collision, or turned on to allow module101 to deploy. When device 11 is “on” (FIG. 2), poles 131, 143, 155 aresimultaneously thrown or actuated to the upper positions. This allowsthe circuit to be completed between module 101 and monitor 119 throughwires 111, 133, 135 and wires 115, 145, 147. At the same time, pole 155activates LED 19 to emit a green light to optically inform the user thatthe airbag 101 is active and ready to deploy.

When device 11 is “off” (not shown), poles 131, 143, 155 aresimultaneously thrown to the lower positions. This interrupts thecircuit between module 101 and monitor 119 at breaks 121, 123. Pole 155activates LED 21 to emit a yellow light to inform the user that airbag101 is inactive and will not deploy.

While the invention has been shown or described in only one of itsforms, it should be apparent to those skilled in the art that it is notso limited, but is susceptible to various changes without departing fromthe scope of the invention. For example, the device shown and describedcould be easily reconfigured for multiple airbag modules, multipleigniters or any combinations thereof.

What is claimed is:
 1. In a motor vehicle airbag system, having a modulewith a plurality of igniters for causing an airbag to inflate, amulti-function vehicle system computer that monitors the status of themodule, and first and second wires extending between each of theigniters and the vehicle system computer for conveying signals betweenthe module and the vehicle system computer, the improvement comprising:a manually operable switch having portions connected to each of thefirst wires, for selectively providing continuity in the first wiresbetween the multi-function vehicle system computer and each of theigniters while in an on position and breaking continuity of the firstwires between the vehicle system computer and each of the igniters whilein an off position; and a resistor connected to each of the second wiresand connected to the switch, so that while in the off position, theswitch places the resistors in series between the first and second wiresand the vehicle system computer, each of the resistors having animpedance similar to that of one of the igniters, so as to provide afalse indication to the vehicle system computer that the continuityexists with the igniters while the switch is in the off position.
 2. Theairbag system according to claim 1, further comprising an optical signaldevice connected to the switch that provides an optical signal while theswitch is in the off position.
 3. The airbag system according to claim1, wherein the switch portions comprise a pole for each of the firstwires, the poles being movable in unison when the switch moves betweenthe on and off positions.
 4. The airbag system according to claim 1,further comprising: a housing adapted to be mounted within a motorvehicle, the switch and the resistors being located within the housing,the switch having a manual engagement portion located on an exterior ofthe housing for engagement by a user.
 5. The airbag system according toclaim 1, further comprising: a housing adapted to be mounted within amotor vehicle, the switch and the resistors being located within thehousing, the switch having a manual engagement portion located on anexterior of the housing for engagement by a user; and an optical deviceconnected to the switch that provides an optical signal while the switchis in the off position, the optical signal device being mounted to theexterior of the housing.
 6. In a motor vehicle airbag system, having amodule with a plurality of igniters for causing an airbag to inflate,the igniters each having an impedance of predetermined value, amulti-function vehicle system computer that monitors the status of themodule and registers a fault if the impedance of the igniters in themodule varies from the predetermined value, and first and second wiresextending between each of the igniters and the vehicle system computerfor conveying signals between the module and the vehicle systemcomputer, the improvement comprising: a break in each of the firstwires, interrupting continuity between the vehicle system computer andeach of the igniters; a housing adapted to be mounted in a passengercompartment of the motor vehicle; a pair of leads for each of the firstwires, the leads of each pair having ends connected to one of the firstwires on opposite sides of the breaks, each pair of leads extending intothe housing; a manually operable switch mounted in the housing andhaving a manual engagement actuator on an exterior of the housing, theswitch having a pole for each igniter, each of the poles being connectedto one of the leads of each of the pairs, each of the poles having an onposition that connects the leads of each of the pairs together forproviding continuity between the vehicle system computer and each of theigniters, each of the poles having an off position that breaks theconnection between the leads of each of the pairs; a resistor mounted inthe housing for each of the igniters, each of the resistors beingelectrically connected to each of the second wires and connected to theswitch, so that while in an off position, the poles place the resistorsin a series between the first and second wires and the vehicle systemcomputer, each of the resistors having an impedance similar to that ofone of the igniters so as to avoid the register of a fault by thevehicle system computer while the switch is in the off position.
 7. Theairbag system according to claim 6, further comprising: an opticalsignal device connected to the switch that provides an optical signalwhile the switch is in the off position, the optical signal device beingmounted to the exterior of the housing.
 8. The airbag system accordingto claim 7, wherein the switch has three poles and is a double-throw. 9.A method of preventing the registering of a fault signal in a vehiclesystem computer controlling airbag deployment of a motor vehicle airbagsystem, the airbag system including a module with a plurality ofigniters for causing an airbag to inflate, the vehicle system computermonitoring the status of the module and registering a fault signal ifthe impedance of the igniters in the module varies from thepredetermined value, and first and second wires extending between eachof the igniters and the vehicle system computer for conveying signalsbetween the module and the vehicle system computer, the methodcomprising: severing each of the first wires between the igniters andthe vehicle system computer, creating a pair of ends for each of thefirst wires; connecting a portion of a manually operable switch betweenthe ends of each of the first wires; connecting one side of a resistorto each of the second wires and the other side to the switch, each ofthe resistors having an impedance similar to that of one of theigniters; placing the switch in an on position, providing continuity inthe first wires between the vehicle system computer and each of theigniters; then placing the switch in an off position, breakingcontinuity in the first wires between the vehicle system computer andeach of the igniters and simultaneously placing the resistors in seriesbetween the first and second wires and the vehicle system computer, eachof the resistors having an impedance similar to that of one of theigniters, so as to prevent the vehicle system computer from registeringa fault signal by providing impedance with the predetermined value whilethe switch is in the off position.
 10. The method as recited in claim 9,further comprising: providing an illuminated signal while the switch isin the off position.